Rolling consolidation of metal matrix composites

Abstract Transverse rolling of metal matrix composite precursor wires is proposed as a consolidation technique for making sheets. Rolling in the transverse direction to the fiber orientation is analytically shown to be feasible, and longitudinal rolling results in fiber breakage. Plasticity analysis is conducted using Hill's general yield criterion for an isotropic materials and the associated Levy-Miles equations modified for plane strain conditions. The slab method is used to calculate the stresses in the material, and the effects of rolling parameters on the principal stress ratio are investigated. At the microscopic level, an elastic-plastic finite element formulation and a computation procedure are presented. Individual fibers are modeled to determine the stress state around each fiber. The principal stress ratio is suggested as a parameter that determines the tendency for void formation due to debonding and fiber breakage; finite element analysis is used to determine the effects of the principal stress ratio on the fiber-matrix interfacial stresses in the micromechanics model. The analysis determines the deformed mesh, plastic zone propagation and the stresses at the interface as a function of volume fraction and principal stress ratio. Interfacial stresses are assumed to be responsible for debonding during the deformation of metal matrix composites. This assumption and the results of the analysis provide guidelines for defining, the level of the biaxial stress field in the plane transverse to the fibers during rolling that will minimize interfacial fiber-matrix stresses.

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